The present invention relates to a method for producing separating nozzle elements for separating gaseous mixtures, particularly isotope mixtures, the nozzle element being of the type composed of a separating body, and end plates, with separating structures passing through the separating body to define separating chambers and gas flow conduits, and the end plates being provided with openings for the flow of gas into and out of the separating body.
When separating components, e.g. isotopes, of a gas mixture with a separating nozzle, the gas pressure leading to minimum specific energy consumption is inversely proportional to the characteristic dimensions of the separating structure, as disclosed in the publication Chemie Ing. Technik [Chemical Engineering Technology] Vol. 39 (1967) at page 4. Since the specific costs for the compressors, conduits and valves required to perform this method decrease considerably with increasing gas pressure, it is desirable to make the separating nozzle structure as small as possible. An inlet pressure of e.g. 0.5 bar here corresponds to a skimmer slot width of only about 10 .mu.m.
It is known to produce separating nozzles with particularly small characteristic dimensions by assembling them of a stack of mutually aligned foils each of which is provided with a plurality of passages having the cross-sectional configuration of the gas inlet channel, the curved Laval nozzle, the skimmer and the discharge channels, as described in U.S. Pat. No. 3,853,528. According to preferred forms of construction, the shape of the passages is etched out in the foils.
To achieve a further reduction in size of the separating nozzle structure for the reasons mentioned above, the requirements for accuracy in the mutual alignment of the foils increase in correspondence with the reduction in size of the structure. At the same time, due to the increasing pressure differences between the various regions of the separating structures, the leakage currents which cannot be completely avoided increase along the foil surfaces.